Na掺杂量对ZnO薄膜AFM图像多重分形谱的影响

用溶胶-凝胶法在Si（111）基片上制备Na掺杂ZnO薄膜,利用原子力显微镜（AFM）观察薄膜的表面形貌,采用多重分形理论定量表征薄膜的AFM图像。结果显示：随着Na含量的增加,薄膜平均颗粒尺寸逐渐增大,表面RMS粗糙度从7.4 nm增大到44.4 nm,分形谱宽Δα从0.059增大到0.200,说明薄膜表面高度分布不均匀程度逐渐增大;所有样品的Δf值均大于零,表明薄膜表面沉积于最高峰的原子数多于最低谷的原子数。     

Li、Mg掺杂ZnO薄膜PL特性研究

采用溶胶-凝胶法在玻璃基片上制备了Li、Mg掺杂的ZnO薄膜,研究了薄膜的光致发光(PL)性能。结果表明,由氧缺位引起的深能级发光峰(450~470 nm)的强度随Li和Mg掺杂量的增加而下降。Mg的添加会使薄膜的带边发射(NBE)增强,而Li的掺杂抑制了NBE峰,同时引发403 nm的Li杂质能级峰,该能级位于价带顶0.29 eV处。     

氧氩流量比对RF溅射ZnO:Mg薄膜结构及光学性能的影响

利用射频(RF)磁控溅射技术,采用单质Zn靶和 MgO陶瓷靶共溅射,在O₂和Ar气的混合气氛下制备了Mg掺杂ZnO(ZnO:Mg)薄膜,并通过改变O₂和Ar的流量比O ₂/Ar,研究了 对ZnO:Mg薄膜的物相结构、表面形貌及光学性能的影响。结果表明,室 温下O₂/Ar在1∶1～3∶1 范围内制备的薄膜均为单相的ZnO(002)薄膜,薄膜具有三维(3D)的结核生长模式;沉积的 ZnO:Mg薄膜在 N₂氛下200℃退火处理后,O₂/Ar为3∶1制备的薄膜在380～1200nm光谱范围内具有较高的透过率,可见光区平 均透过率约为85%、最大透过率达90%;薄膜的光学带隙 Eg为3.51eV,Mg掺杂对ZnO薄膜的光学带隙具有 较为明显的调制作用;采用极值包络线法计算表明,薄膜在589.3nm 处的折射率为1.963,膜厚约285nm。     

Al掺杂ZnO薄膜的表面形貌和光学性质

用原子力显微镜、紫外-可见分光光度计和荧光光谱仪观察采用溶胶-凝胶法制备的Al掺杂ZnO薄膜的表面形貌、透射光谱和光致发光谱.结果表明,Al掺杂量为0.5at 9/6的ZnO薄膜经550℃退火处理后,粗糙度为1.817,Al掺杂量为1.0at%的ZnO薄膜经600℃退火处理后,粗糙度增大到4.625.样品在可见光范围内的平均透过率均大于80%.当激发波长为325 nm时,在397 nm(3.13 eV)附近出现紫外发光峰;当激发波长为360 nm时,在443 nm(2.80 eV)附近出现蓝色发光峰.探讨了样品的蓝光发光机制.     

sol-gel法制备掺Al的ZnO薄膜及其表面形貌表征

用原子力显微镜,观察了sol-gel法制备之掺Al的ZnO薄膜的表面形貌,计算了薄膜的表面高度–高度相关函数H(r)-r,并用分形表面高度–高度相关函数的唯象表达式,对薄膜表面高度–高度相关函数进行拟合。结果表明:掺Al的ZnO薄膜表面具有典型的分形特征,Al掺杂量的增加和退火温度升高,使掺Al的ZnO薄膜的表面粗糙度w从1.39增大到5.47,分形维数Df由2.12减小到2.08,水平相关长度ξ从31.25增到76.17。     

溶胶-凝胶法制备Co,Cu共掺杂ZnO薄膜 结构及光学特性

采用溶胶-凝胶法在玻璃基片上制备了纯ZnO薄膜和高浓度Cu掺杂的Co,Cu共掺ZnO(Zn0.90CoxCu0.1-xO,x=0.01,0.03,0.05)薄膜。扫描电镜观察到无论是纯ZnO还是掺杂ZnO薄膜表面都有均匀分布的颗粒,但是在Cu含量较高时均匀性更好。X射线衍射揭示所有样品都具有纤锌矿结构,但是Cu掺杂量的增加使晶格常数略有减小,而晶粒尺寸却略有增大。XPS测试结果表明样品中Co离子的价态为+2价和+3价,Cu离子的价态为+2价和+1价共存。室温光致发光测量在所有样品中均观察到较强的紫外发光峰、蓝光双峰和较弱的绿光发光峰。     

Co与Cu掺杂ZnO磁性薄膜的溶胶-凝胶旋涂法制备

用溶胶-凝胶旋涂法在玻璃衬底上制备了Co,Cu单掺杂及(Co,Cu)共掺杂ZnO薄膜.磁性测量表明,无论是单掺还是共掺的ZnO薄膜都具有室温铁磁性,且Co掺杂和共掺杂ZnO薄膜的磁性相近,而Cu单掺ZnO薄膜磁性稍弱一点.用原子力显微镜和X射线衍射研究了Co,Cu掺杂对ZnO薄膜表面形貌和晶体结构的影响,在薄膜中没有发现第二相和磁性团簇的存在,且所有ZnO薄膜样品都存在(002)择优取向.室温光致发光测量在所有的样品中都观察到447和482 nm附近的蓝光发射,认为是由于氧空位浅施主能级上的电子到价带上的跃迁所导致的.     

Al掺杂ZnO薄膜原子力显微图像的多重分形研究

用原子力显微镜观察溶胶-凝胶法制备Al掺杂znO薄膜的表面形貌,运用多重分形理论研究Al掺杂ZnO薄膜的原子力显微图像,多重分形谱可以很好地定量表征薄膜的表面形貌.结果显示:Al掺杂量为0.5 at.%的ZnO薄膜经550℃退火处理后,rms粗糙度为1.817,Al掺杂量为1.0 at.%的ZnO薄膜经600℃退火处理后,rms粗糙度增大到4.625,相应的分形谱宽△α从0.019增大到0.287,分形参数△f由-0.075变为0.124.     

ZnO多晶薄膜绒面结构及陷光特性分析

针对当前薄膜太阳电池对光管理的迫切需求,采 用磁控溅射及后腐蚀技术制备获 得了高性能绒 面铝掺杂氧化锌(AZO,ZnO:Al)前电极。深入分析了ZnO多晶薄膜厚度及腐蚀时间对绒面 结构及陷光特性的影响。研究 结果表明,随多晶薄膜厚度的增加,晶粒尺寸增大,腐蚀后获得的弹坑状表面结构的粒径亦 随之增大,绒 度增大;随后腐蚀时间的增加,弹坑状粒径及绒度均具有先增大而后趋于饱和的趋势。当沉 积ZnO多晶 薄膜初始厚达2μm时,获得的薄膜电阻率小于3×10－4 Ω· cm,经180s稀HCl(0.5%)腐蚀后,绒面 ZnO 的均方根粗糙度(RMS)达143nm, 400～ 1100nm平均透过率达81.4%, 在500nm处绒度为84.3%nm处绒度可达73.8%,方块电阻小于5Ω/□,满足了硅基 薄膜叠层电池对前电极的光电性能需求。     

p型掺杂ZnO薄膜的光致发光特性研究

采用磁控溅射技术,以N2作为p型掺杂源,制备p型N掺杂ZnO薄膜,着重研究了不同掺杂量的N掺杂ZnO薄膜的光学特性。结果表明,掺杂ZnO薄膜在360 nm、380 nm处出现主荧光峰,409 nm、440 nm处出现次荧光峰,而且随着N掺杂量的不同,主、次荧光峰 峰位和强度都会发生变化。当O2∶N2的体积流量比为15∶5时,薄膜中N含量最大,荧光谱中发光峰强度最佳,霍尔效应检测薄膜具有明显的p型导电特征。     

溶胶-凝胶法制备氧化锌薄膜的研究

采用溶胶-凝胶法在锌片和硅片表面制备氧化锌薄膜.采用XRD、SEM等分析测试手段对比了不同的配置比和衬底对氧化锌薄膜的相组成和显微形貌的影响.实验结果表明:与Si片相比,Zn片衬底对样品的衍射峰幅度产生一定的影响;所制备出来的样品都在衍射角2θ=34.4°附近出现衍射峰;当Zn2+浓度不同时,得到的ZnO薄膜的形貌不同.     

Al掺杂半导体Mg2Si薄膜的制备及电学性质

采用磁控溅射方法和热处理工艺在Si衬底上制备了不同Al质量分数的Mg2Si薄膜,研究了不同Al质量分数对Mg2Si薄膜结构及其电学性质的影响.通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)和四探针测试仪对Al掺杂Mg2Si薄膜的晶体结构、表面形貌和电学性质进行表征和分析.结果表明:采用磁控溅射技术在Si衬底上成功制备了不同Al质量分数的Mg2Si薄膜,样品表面表现出良好的连续性,在Mg2Si (220)面具有择优生长性.随着质量分数的增加,结晶度先增加后降低,晶粒尺寸减小,且在Al质量分数为1.58％时结晶度最好.此外,样品电阻率也随着Al质量分数的增加逐渐降低,表明Al掺杂后的Mg2Si薄膜具有更好的导电性,这对采用Mg2Si薄膜研制半导体器件有着重要的意义.     

Microstructure and electrical properties of nitrogen doped 3C–SiC thin films deposited using methyltrichlorosilane

The growth, microstructure and electrical properties of in-situ nitrogen doped 3C–SiC (111) thin films for sensor applications are presented in this paper. These thin films are deposited at a pressure of 2.5 mbar and temperature of 1040 °C on thermally oxidized Si (100) substrates from methyltrichlorosilane (MTS) precursor using a hot wall vertical low pressure chemical vapor deposition (LPCVD) reactor. Ammonia (NH₃) is used as the nitrogen doping gas. The sensor response depends on chemical composition, structure, morphology and operating temperature. The above properties are investigated for all in situ nitrogen doped (0, 9, 17 and 30 at% of nitrogen) 3C–SiC thin films using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and four probe method. The XRD patterns of the 3C–SiC thin films show a decrease in the crystallinity and intensity of the peak with increase in dopant concentration from 0 to 17 at%. AFM investigations show an improvement in the grain size of the nitrogen doped 3C–SiC thin films with increase in nitrogen concentration from 0 to 17 at%. The sheet resistance of nitrogen doped 3C–SiC thin films is measured by the four probe technique and it is found to decrease with increase in temperature in the range of 40–550 °C. The resistivity and average temperature coefficient of resistance (TCR) of doped 3C–SiC thin film deposited with 17 at% of nitrogen concentration are found to be 0.14 Ω cm and −103 ppm/°C, respectively and this can be used as a sensing material for high temperature applications.     

Study of Structural,Electrical and Optical Properties of (200)-Oriented CdTe Thin Films Depending on the Post-deposition Low Temperature

Cadmium telluride nanoparticles (CdTe NPs) have been synthesized by a sonochemical technique, deposited on glass and quartz glass at 100°C and 2.7?×?10^?6 kPa and then studied by analyzing the x-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), current–voltage test (I–V) and scanning electron microscopy (SEM). The XRD results indicated the formation of a strong preferential (200) orientation of CdTe with a cubic zinc-blende structure on both substrates. In order to show the effect of heating on the structure and optical properties of the prepared thin films, they were annealed at temperatures of 50°C, 70°C and 100°C for 1 h. It was found that the grain size in this orientation increases with the increase of the temperature. In addition, the obtained optical band gap energies by UV–Vis measurements were in the range of 1.46–1.53 eV. The electrical properties of the prepared films were observed to increase with annealing using I–V measurements. The thin films were also found to be uniform with a small particle size, as revealed by SEM.

     

Effects of Mg additions on the electromigration behavior of Al thin film conductors

Aluminum thin film conductors containing Mg alloying additions have been tested for electromigration failure by formation of electrically open circuits. The test conditions were either 2 × 10⁶ A/cm² or 4 × 10⁶ A/cm² for the current density, and either 175 or 225°C for the temperature. The median lifetimes were found to increase with increasing Mg concentrations up to the highest concentration tested, about 6%. With polycrystalline films the maximum increase in lifetime resulting from Mg additions corresponds to a factor of about 100, as compared to pure Al films. This is about equal to previously reported results obtained with Cu additions. The increase in lifetime has been shown to result from a decrease in the rate of grain boundary diffusion for the Al atoms. Magnesium atoms diffuse at approximately the same rate as Al atoms. Thus the mechanism of failure formation in Al films containing Mg is thought to be different than in Al-Cu films, where Cu atoms diffuse faster than Al atoms and failure ensues upon local Cu depletion.     

Effect of preheating and annealing temperature on the microstructure and optoelectronic properties of CZTS films prepared by sol-gel method

The effects of different preheating and annealing temperatures on the surface morphology, microstructure, and optical properties of Cu2ZnSnS4 (CZTS) thin films are investigated by controlling the preheating and annealing temperatures. The prepared thin films were characterized using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and ultra-violet-visible (UV-Vis) spectroscopy techniques. XRD and Raman spectroscopy showed that a Kesterite structure with a selective orientation along the (112) peak was generated, and the thin films produced at a preheating temperature of 300 °C and annealing temperature of 570 °C had fewer secondary phases, which was beneficial for improving the performance of the solar cells. SEM confirms that the crystallite size increases and then decreases as the temperature increases, and the largest and most uniform crystallite size with the smoothest surface is generated at the above preheating and annealing temperatures. UV-Vis measurements show that the thin films generated at the above temperature have the lowest transmittance and the lowest optical band gap value of 1.46 eV, which is close to the optimal band gap value for solar cells and is suitable as an absorber layer material.     

Low-Temperature Synthesis of High-Adhesion Cu(Mg) Alloy Films on Glass Substrates

Cu(0.5 at.%Mg) alloy films were deposited on glass substrates, and annealed at 200–400 °C in vacuum. The resistivity of the Cu(Mg) films was reduced to about 3.0 μΩcm after annealing at 200 °C for 30 min, and the tensile strength of adhesion of the Cu(Mg) films to the glass substrates was increased to 30–40 and 35–55 MPa after annealing at 250 and 300 °C, respectively. The reduction in resistivity can be explained as reduced impurity scattering and grain-boundary scattering, since Mg segregation to the film surface and Cu(Mg)/glass interface, and consequent Cu grain growth, were observed. Increased adhesion of the Cu(Mg) films to glass substrates after annealing was also explained by the strong segregation of Mg atoms, and the formation of a reaction layer at the interface. Mg atoms were observed to have reacted with the glass substrates and formed a thin crystalline MgO layer at the interface in the samples annealed at 300 °C, while Mg atoms were highly concentrated above the Cu(Mg)/glass interface without oxide formation at the interface in the samples annealed at 250 °C. Thus, the process temperature and time to obtain low-resistivity and high-adhesion Cu alloy films on glass substrates could be reduced to 250 °C and 30 min using Cu(Mg) films.     

The effects of hydrogen on aluminum-induced crystallization of sputtered hydrogenated amorphous silicon

The effects of hydrogen on aluminum-induced crystallization (AIC) of sputtered hydrogenated amorphous silicon (a-Si:H) were investigated by controlling the hydrogen content of a-SiH films. Nonhydrogenated (a-Si) and hydrogenated (a-Si:H) samples were deposited by sputtering and plasma-enhanced chemical vapor deposition (PECVD). All aluminum films were deposited by sputtering. Hydrogen was introduced into the sputter-deposited a-Si films during the deposition. After deposition, the samples were annealed at temperatures from 200°C to 400°C for different periods of time. X-ray diffraction (XRD) patterns were used to confirm the presence and degree of crystallization in the a-Si:H films. For nonhydrogenated films, crystallization initiates at a temperature of 350°C. The crystallization of sputter-deposited a-Si:H initiates at 225°C when 14% hydrogen is present in the film. As the hydrogen content is decreased, the crystallization temperature increases. On the other hand, the crystallization initiation temperature for PECVD a-Si:H containing 11at.%H is 200°C. Further study revealed that the crystallization initiation temperature is a function, not only of the total atomic percent hydrogen in the film, but also a function of the way in which the hydrogen is bonded in the film. Models are developed for crystallization initiation temperature dependence on hydrogen concentration in a-Si:H thin films.     

Silicon wafer wettability and aging behaviors: Impact on gold thin-film morphology

This paper reports on the wettability and aging behaviors of the silicon wafers that had been cleaned using a piranha (3:1 mixture of sulfuric acid (H₂SO₄, 96%) and hydrogen peroxide (H₂O₂, 30%), 120 °C), SC1 (1:1:5 mixture of NH₄OH, H₂O₂ and H₂O, at 80 °C) or HF solution (6 parts of 40% NH₄F and 1 part of 49% HF, at room temperature) solution, and treated with gaseous plasma. The silicon wafers cleaned using the piranha or SC1 solution were hydrophilic, and the water contact angles on the surfaces would increase along with aging time, until they reached the saturated points of around 70°. The contact angle increase rate of these wafers in a vacuum was much faster than that in the open air, because of loss of water, which was physically adsorbed on the wafer surfaces. The silicon wafers cleaned with the HF solution were hydrophobic. Their contact angle decreased in the atmosphere, while it increased in the vacuum up to 95°. Gold thin films deposited on the hydrophilic wafers were smoother than that deposited on the hydrophobic wafers, because the numerous oxygen groups formed on the hydrophilic surfaces would react with gold adatoms in the sputtering process to form a continuous thin film at the nucleation stage. The argon, nitrogen, oxygen gas plasma treatments could change the silicon wafer surfaces from hydrophobic to hydrophilic by creating a thin (around 2.5 nm) silicon dioxide film, which could be utilized to improve the roughness and adhesion of the gold thin film.     

Effect of low energy proton beam irradiation on structural and electrical properties of ZnO:Al thin films

In this study, we report the structural modification and change in electrical behaviour of aluminium doped zinc oxide by low energy (100 keV) proton irradiation. Aluminium doped zinc oxide films were deposited using DC magnetron sputtering and then annealed for a short duration at 600 °C before irradiation. Structural and defect studies of the films carried out using XRD and Raman spectroscopy. It suggests that the crystalline ordering increases at higher fluences due to annealing of defects in the film. The increase in crystallinity at higher fluences decreases the grain boundary scattering and causes low resistivity. There is no significant change in carrier concentration after the irradiation, however the mobility and resistivity of the Al doped ZnO films change with proton irradiated fluences. The development of defect due to irradiation has been confirmed through Raman spectroscopic studies. The increase in activation energy of particles has been suggested by low energy proton irradiations at higher fluences in the annealed Al doped ZnO thin films. The uniform particle distribution increases with fluences of the irradiation that may be helpful for spintronics and sensor device technology.